How to make a scale of multiple choice questions?

I have this scale form an article (unfortunately doesnt say what they did to make all items into one scale) its composed of 6 questions 4 multiple choice and 2 yes/no. How do i put these together to make a new variable because they are all part of the same construct. FOr example the multiple choice questions are 1. How much info about a product do you share with your friends? a. alot b. average. a little ? So 4 questions are like this and the other 2 are yes/no. How do I make one constrcut item from these in spss? Greatly appreciate your help!
It seems that your multiple choice questions are really a form of a likert scale. Depending on what the questions are, you probably want to treat the likert questions separately from the yes/no questions.

But if you really want to combine them (and maybe that's OK depending on the type of questions being asked), you could treat the yes/no as the extremes of the likert scale. So the mutliple choice are 1-2-3 and the yes/no are 1-3.

I probably wouldn't combine them, but it is an option I suppose.